Flexure (bending) is often the critical mode of failure
in concrete floors; therefore the moment capacity of the floor is very
important. As concrete has a very low tensile strength relative to its
compressive strength, it can very easily crack and fail on the edge which is in
tension. Therefore, any concrete element which is subject to significant
bending moments requires reinforcement with a material which is strong in
tension (usually steel).
Two simple ways to increase the moment capacity of an
- Increase the amount of reinforcement in the
- Increase the depth of the element to increase
the lever arm of the force exerted by the reinforcement.
Finding the moment
capacity of steel and macro-synthetic fibre-reinforced concrete is more complex
than the methods used in calculating capacities of traditional reinforced
concret. This is because it requires a notched beam test to be conducted with
the actual fibre to be used in the design. The test acquires values of fR1,
fR2, fR3 and fR4 which can be used to carry out
moment capacity analysis on the slab.